Weld-electrode and product



7 F. K. BLOOM 2,802,756

' WELD-ELECTRODE AND PRODUCT Original Filed April 2, 1947 or //.6z-2.62; Ni incidenfa/s to 9. 9% Mn inc/denials to 26.32

0 away-219% I Iron remamder; with Or exceeding lVi-r-Mn; and mm 20gm/4.38m Mn) 7.5 zc //6-/89;"

pr eferab/y /22-/a9.

/ INVENT OR Fredr/b/r M. Bloom Ba 4 jar ATTORNEY 2,802,753 Patented Aug.13, 1957 United Sttes Patent Office wELn-ELEcrRonE AND PRODUCT FredrickKenneth Bloom, Baltimore, Md, assignor to Armco Steel Corporation, acorporation of Ohio Continuation of application Serial No. 738,949,April 2, 1947. This application January 21, 1953, Serial No. 332,532

2 Claims. (Cl. 117-407) This application is a continuation of myapplication Serial No. 738,949, filed April 2, 1947, and entitledElectrode and Deposit, now abandoned, and the invention relates todeposit welding, more especially to metal products having corrosionresistant thermally deposited facings and to a process and manufacturesfor giving the products.

Among the objects of my invention is the provision of a simple, directand reliable methodfor producing hard facing deposits, as for exampledeposits on a plain carbon steel base, which deposits are initially softwhen laid down and are extremely tough and which 'on the application ofcold work become highly resistant to abrasion, particularly whereabrasion associated with severe impact is of importance. The method isalso well suited for giving corrosion resistant surfaced products,further having resistance to abrasion and heat as well as being crackresistant at the interface with the parent metal and in the body of thesurfacing metal.

Other objects in part will be obvious and in part pointed outhereinafter.

The invention accordingly consists in the combination and proportionmentof elements, composition of materials and features of construction, andin the several steps and the relation of each of the same to one or moreof the others as described herein, the scope of the application of whichis indicated in the following claims.

As conducive to a clearer understanding of certain features of myinvention, it may be noted at this point that facings achieved bydeposit surfacing or welding operations, where fulfilling a class ofneeds, represent an easy and economical means for keeping equipment ingood operating condition and free of often repeated shut-down and repairor replacement of parts. Quite often, these facings are thermallydeposited from a welding rod and onto a suitable metallic base, such asonto old or new carbon steel parts which require protection for reasonsof intended use, and the facings amount to a surface, edge, point, orthe like,which is better adapted for serving desired functions than theunderneath metal. These facings, when hard, are in demand for fulfillingany of a wide variety of functions as where requirements includeresistance to abrasion and impact. Hard facings originally wereintroduced on such products as metal working dies, oil well drillingtools, certain types of excavating equipment, and the like, butadditional uses soon were found so that now the 'art of deposit weldingis an important factor involved in many production and maintenancetechniques, and in a large variety of specific industries and products.

An existing objection to many of the heretofore hard facings, however,is their susceptibility to corrosion; the rate of corrosion being sorapid where corrosive atmospheres, liquids or solids are encounteredthat initial cost of including the facing on a particular product isprohibitive. In producing certain of the prior art hard facings bydeposit welding, the added metal has a strong tendency to crack at theinterface formed with the base metal or between deposited beads of theweld. This detriment too frequently arises by reason of particularcomposition of the deposited metal. Some of the facings are highlysusceptible to cracking because of hot-shortness, this too revertingback to composition of weld rod or electrode employed. The occurrence ofcracking sometimes becomes so objectionable as to render further use ofa given welding composition undesirable for hard facing purposes or isoften responsible for losses in production or for costly replacement ofparts because of failure or inadequacy of the cracked hard facing metal.

The matter of hardness of the deposited metal is frequently a limitingfactor with regard to utility of the hard faced article or product; thisis especially so where resistance to abrasion or scour is ofconsiderable importance. It follows, however, that certain of the priorart hard facing materials serve well when exposed to wearing andoperating influences, but fail far too readily where usage includesexposure to impact. There are occasions too Where the hard facing metalis needed for fulfilling uses where the combined influences of abrasionand impact are brought into effect and where failure through a lackingresistance to either negatives utility.

An outstanding object of my invention accordingly is the provision ofstainless steel hard facing rods which are readily produced as from thestandpoint of producing the metal thereof and making the rods to desiredcontent; also the production of strong and impact resistant stainlesssteel hard fa-ced products which resist cracking, wear and abrasion.

Referring now more particularly to the practice of my invention, Iprovide metal products, as for example carbon steel products of low,medium, or even high carbon grade, having a strong and durable stainlesssteel facing. For depositing the facing, I frequently produce and employa weld rod, illustratively an arc welding electrode, source of thefacing metal. The stainless steel in the facing has a criticalcomposition, and as initially deposited is substantially fullyaustenitic considering too that carbides may be present withoutdetriment. A small amount of ferrite usually exists in the facingcomposition and is believed to contribute somewhat to the prevention ofcracking. Further, the initially deposited metal is soft, but theaustenite by reason of having a tendency toward instability, readilytransforms to martensite when the metal is subjected to cold working asmight be encountered during use. The cold working or work hardeninggives a hard, corrosion-resistant skin on the facing which resistsabrasion; the underlying portion of the facing metal remains relativelysoft, but is tough and highly resistant to impact. I rely upon theconditions of use to achieve the work-hardened surface, thus developinga hard, abrasion-resistant skin or facing.

For the reason that losses sometimes occur in welding and facingoperations, the composition of the facing rod which I provide is givenin terms of the facing desirably obtained. The rod or electrode is of.such composition as to yield a deposit of facing alloy, comprising about10% to 22% chromium, nickel from small and fractional percentages under1% and ranging up to about 9%, from small or incidental amounts up toapproximately 18% manganese, about 0.10% to 1.5% carbon, and theremainder substantially all iron. At the same time, however, I restrictthe amounts of chromium, nickel, manganese and carbon in the rod toamounts which ensure inbefore described which satisfies the formula.

that the ratio or relationship of these elements in the hard facingobtained is substantially consistent with the following empiricalformula:

Percent Mn 2 =21 numerical value exceeding approximately 95 minimum. Thenumerical values preferably range between 100 and 155. As the minimumnumerical value of the formula is approached from the high side, theaustenitic quality of the facing tends to disappear and the property ofinitial softness suffers. An excessive increase in alloy content of thefacing, away from the minimum numerical value of the formula impairs thework hardening characteristics. 7

The welding rod preferably includes a coated stainless steel wire corehaving contents of the core and coating suflicient, in view of possiblelosses while forming the deposit to give a facing composition of thecharacter here- I find considerable advantage in making the corefrom'any one of the standard types of stainless steels, noted below inTable 1, any ofthese being readily provided and illustratively hotworked to desired size and shape.

TABLE I 7 Percent Gr (Percent Ni+ 10 (Percent Percent Cr Ni 0. 35 Max.

. Max. Max.

I coat the core with flux as by continuously feeding a wire of the coremetal through a suitable flux extruding die, and extruding on the fluxmixed with a suitable binder. The coating preferably issubstantiallyfree of hydrogen-yielding constituents, and illustrativelyincludes a 7 dehydrated mineral slag-forming material having acomposition of the character more particularly set forth in thecopending George E. Linnert application, Serial No. 565,573, filedNovember 28, 1944, now U. S. Letters Patent No. 2,544,334 of March 6,1951-. For building up the rod composition, I sometimes add amounts ofany needed elements to the coating, as for example amounts of manganeseand carbon in the form of powdered ferromanganese or chromium and nickelin the form of chromium-nickel ferroalloy. Powdered graphite sometimesis introduced in the coating as a source of carbon. The materialsconveniently are applied in mixture with the flux to the core. At times,the coating is substantially all flux, the core for example in thisinstance being the entire source of metal, or even at times I use thecores, as rods, without the flux coating.

When the protection from oxidation is reasonably good, the recoverieswhich may be expected from the several alloy ingredients mentioned aboveare approximately as follows: Carbon 75%, chromium 95%, nickel 100%,manganese 75%. The dilution had in laying down a facing on a mild steelbacking averages about 25%.

It is seen from calculation that the weld rod or electrode compositioncomprises, in total, about 11.6% to 25.6% chromium, nickel upto' about9.9%, manganese limits alfe'ady noted.

up to abet: 26.3%, about 0.16% 062.19% carbon, and the remaindersubstantially all iron. In addition, the amount of hromium, nickel,manganese and carbon are found restricted to a relationship whichexpressed in terms of the weld rod or electrode composition, is asfollows: percent Cr (percent Ni+.38 (percent Mn)+7.5 (percent C))=anumerical. value in excess of 116, and preferably ranging between 122and 189.

The austenitic work hardenable or martensitic Work hardened deposits orfacings on the metal products which I achieve, therefore, in view of thenature of the source of the deposit metal, have a stainless steelcomposition falling within the broad percentage ranges of ingredientsgiven hereinbefore and also within the formula ratio In producing thestainless steel facings, the deposited metal by reason of criticalcomposition resists cracking at the interface withthe mild carbon steelbase. As a matter of further importance, the facing, where produced bydepositing beads of the stainless steel as by electric arc-weldingmethods, resists cracking at the points of interbeading and also resistscracking in use when hot or cold. I usually maintain a minimum of suchresidual elements as sulphur and phosphorus in the electrodes .and inthe facings obtained, for enhancing the resistance to cracking. Thedehydrated mineral flux coating whichfI prefer to use contributes to theform of gears, piuions, slides and guides for machinery such as engineshandling gravel, rocks, and other impactproducing materials'as in miningmachinery where severe abrasion and acid, or chemical-laden waters arepresent.

Also, I produce hard'faced products which are useful where high velocityliquids laden with solids are contacted.

Parts for pumps and suction dredges are among the latter products. Incertain instances the products which I achieve fall into a classaffording prolonged life, and where the life is. extended indefinitelyby renewing the hard facing from time to time. Other products are highlyimpact resistant plow shares and steam shovel teeth for rocky soils,crusher rolls, liners and balls for ball mills where heavy hardmaterials are being ground, pulverizer hammers, searifier teeth for roadbuilding and maintenance machinery, and power clutches and clutch partsfor resisting impact, wear and the like. A great number of otherproducts of course could be named; however, for purposes of illustrationit is believed that the above will sufiice.

As illustrative of the practice of my invention, I provide anarc'weldin'g electrode having a core and a coating, in which electrodeor manufacture the carbon, chromium,- nickel and manganese are presentin such amounts as to yield a deposited facing containing these elementsin accordance with any one of the compositions noted below in Table IIor in any other proportions consistent with the general compositionranges and formula hereinbefore set forth. The table relates to facingswhich contain carbon, chromium, nickel andmanganese, only very smallamounts of such elements as sulphur and phosphorus, and

the remainder substantially all iron. Hardness values as V are noted inthe instance of such composition, respectively correspond to the softdeposited condition of the facing and to the subsequent work-hardenedcondition of the surface or skin of the facing metal;

TABLE 11 Hard facing compositions Facing Deposit Rockwell Hardness ofDeposit Formula No. Ratio Soft Work C Cr Ni Mn 136- Hardposited ened 15.68 1. 99 0.72 107 O 20 0 4 1-50 15. 48 1. 99 0. 74 153 C 27 C 50-5216.15 1. 83 3.90 103 O 19 C 42-48 15. 15 1. 83 3. 60 124 C 18 G 43 14.70 1. 78 7. 33 100 O 21 C 51-52 14. 73 l. 78 7. 33 104 G 20 C 44-51 14.64 1. 78 6. 92 107 C 18 C 45-50 14. 70 1.78 7.13 109 C 18 C 41-45 Thecompositions of the electrodes or weld rods employed in laying down thefacing deposits set forth in Table II are given below:

TABLE III Weld rod compositions For best results the surface of theparent metal for receiving the deposit is cleaned of all loose scale,dirt, rust or other foreign substances, this by pickling, grinding,machining, wire brushing or the like. Then by bead deposit welding orany other satisfactory procedure, I employ the electrode for building upa facing on the clean metal surface, the surface illustratively beingthat of a pro-formed plain carbon steel or high alloy steel product. Theamount of current used with the electrode is for example in the range of140 to 160 amperes. I apply enough metal and then hot file and grind orotherwise effect size. As deposited and cooled, the metal is relativelysoft, which property often contributes ease to shaping and sizing theproduct. I put the relatively soft surfaced products into use where theconditions of use supply the work hardening treatment and the consequentdevelop ment of the abrasion-resistant skin.

Facings of exceptionally durable and lasting quality are obtained onproducts of high alloy or low alloy steel, or on other metals or alloys,through the use of my electrodes. Sometimes, I deposit the facings onhardening steels or even on hardened steels. Quite often the metal basereceiving the facing is not materially responsive to hardening heattreatment, or for other reasons is kept in the unhardened condition.

Thus it will be seen that in this invention there are provided a fusiblewelding rod, a method of producing facings and faced products, and thefaced products themselves, in which the various objects noted, togetherwith many thoroughly practical advantages are successfully achieved. Itwill be seen that the rods or electrodes are of such metallic contentsas to give lasting, impact-resistant hard facings which are strong,resistant to cracking and also resistant to abrasion and corrosion.

As many possible embodiments may be made of my invention and as manychanges may be made in the embodiments hereinbefore set forth, it is tobe understood that all matter described herein is to be interpreted asillustrative and not as a limitation.

I claim as my invention:

1. A hard facing electrode for the production of a facing which isinitially soft as deposited but which readily transforms to martensiteupon cold-working comprising a metal core and a coating thereon, saidcore and coating in total essentially consisting of about 11.6% to 25.6%chromium, nickel incidentals up to about 9.9%, manganese incidentals upto about 26.3%, about 016% to 2.19% carbon, with the chromium contentexceeding the sum of the nickel and manganese contents and with therelationship between the chromium, nickel, manganese and carbon contentsfurther restricted to the relationship between empirical formula:percent chromium (percent nickel +38 (percent manganese)+7.5 (percentcarbon))=a numerical value in excess of 116 but not exceeding 189, andthe remainder substantially all iron.

2. A hard facing electrode for the production of a facing which isinitially soft as deposited but which readily transforms to martensiteupon cold-working comprising a stainless steel core, and a dehydratedmineral flux coating for the core, said core and coating togetheressentially consisting of about 11.6% to 25.6% chromium, nickel up toabout 9.9%, manganese up to about 26.3%, about 0.16% to 2.19% carbon,with the chromium content exceeding the sum of the nickel and manganesecontents and with the relationship between the chromium, nickel,manganese and carbon contents further restricted to the relationshipbetween empirical formula: percent chromium (percent nickel +38 (percentmanganese)+7.5 (percent carbon))=a numerical value between 122 and 189,and the remainder substantially all iron.

References Cited in the file of this patent UNITED STATES PATENTS1,893,160 Clarke Jan. 3, 1933 2,050,043 De Golyer Aug. 4, 1936 2,156,298Leitner May 2, 1939 2,156,299 Leitner May 2, 1939 2,156,307 Rapatz May2, 1939 2,240,672 Scherer May 6, 1941 2,436,867 Lee Mar. 2, 1941

1. A HARD FACING ELECTRODE FOR THE PRODUCTION OF A FACING WHICH ISINITIALLY SOFT AS A DEPOSITED BUT WHICH READILY TRANSFORMS TO MARTENSITEUPON COLD-WORKING COMPRISING A METAL CORE AND A COATING THEREON, SAIDCORE AND COATING IN TOTAL ESSENTIALLY CONSISTING OF ABOUT 11.6% TO 25.6%CHROMIUM, NICKEL INCIDENTALS UP TO ABOUT 9.9%, MANGANESE INCIDENTALS UPTO ABOUT 26.3%, ABOUT 0.16%% TO 2.19% CARBON, WITH THE CHROMIUM CONTENTEXCEEDING THE SUM OF THE NICKEL AND MANGANESE CONTENTS AND WITH THERELATIONSHIP BETWEEN THE CHROMIUM, NICKEL, MANGANESE AND CARBON CONTENTSFURTHER RESTRICTED TO THE RELATIONSHIP BETWEEN EMPIRICAL FORMULA:PERCENT CHROMIUM (PERCENT NICKEL +.38(PERCENT MANGANESE)+ 7.5(PERCENTCARBON)=A NUMERICAL VALUE IN EXCESSOF 116 BUT NOT EXCEEDING 189, AND THEREMAINDER SUBSTANTIALLY ALL IRON.